1. Field of the Invention
This invention relates to safety closures for containers and has particular reference to closures including a snap-on cap and safety ring. These closures are frequently called child resistant closures because they tend to prevent children from readily opening the containers.
2. Prior Art
Various safety closures are described in the prior art. For example, the safety closures disclosed in U.S. Pat. Nos. 3,612,322 and 3,693,820 comprise a snap-on cap held in place on a container by a rotary safety ring which must be aligned with the cap in one angular position and pushed downwardly away from the cap before one can remove the cap from the container. The ring is locked around a portion of the cap by fingers, which extend either from the inside of the ring or from the cap, and which fingers fit into a locking groove formed between the ring and cap. The ring is unlocked by aligning it with the cap in one angular position so that the fingers slide through release grooves in the locking groove when the ring is pulled downwardly away from the cap. Then the cap can be removed.
While these safety closures have generally worked well, it has become apparent that the safety ring can be difficult to open by an adult even when the adult knows how to open the closure. Furthermore, these closures are not ideally suited for containers of liquids; the fit between the cap and the mouth of the container is frequently not tight enough to provide a liquid-tight seal. This is true despite the seal element disclosed in U.S. Pat. No. 3,612,322, which just makes the underside of the cap thicker.
The present invention improves the prior closures by, for instance, providing an outwardly directed bead on the safety ring which makes it easier to grip and push down (and up) the safety ring. Thus, people with arthritis and similar afflictions will have less difficulty moving the safety ring down away from the cap. Secondly, this invention discloses an annular protrusion projecting from the underside of the cap which protrusion closely abuts the rim of the container so that the protrusion and rim act as a liquid-tight seal. The seal of the bottle is further improved by a circumferential knob around the neck of the container. The knob prevents the safety ring, and hence the cap locked thereto, from moving upwardly, thereby keeping the annular protrusion close to the rim. Also disclosed herein is an improved safety ring and cap assembly which has no lateral opening between the safety ring and the cap. This improvement removes the opening because it could be used by a child attempting to open the container by forcing his fingers or teeth into the opening. Finally, this invention describes various ways to incorporate on the closure means for counting the number of uses or doses of the container's contents.